Circuit breaker operating mechanism



March 21, 1950 B. P. BAKER CIRCUIT BREAKER OPERATING MECHANISM 2 Sheets-Sheet 1 Filed July 51, 1947 l I f: T

VINVENTOR .Ben a'n/nPBaKer:

ATTORNEY WITNESSES: A; d j/ 7 March 21, 1950 B. P. BAKER 2,501,302

CIRCUIT BREAKER OPERATING MECHANISM Filed July 31, 1947 2 Sheets-Sheet 2 WITNESSES:

INVENTOR Ben 0min PBa/fen ATTORNEY Patented Mar. 21, 1950 CIRCUIT BREAKER OPERATING MECHANISM Benjamin P. Baker, Turtle Creek, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 31, 1947, Serial No. 765,008

Claims. 1

This invention relates to circuit breakers and nore particularly, to operating mechanism there- One object of the present invention is to provide a circuit breaker embodying an improved operating mechanism of the fluid pressure operated type that is simple and rugged in construction and capable of efficient and reliable opera- Another object of the invention is to provide a circuit breaker embodying an improved operating mechanism of the fluid pressure operated type wherein a single acting shock absorber is connected to the operating mechanism in a manner to retard the final movement of the mechanism in both opening and closing directions.

Another object of the invention is to provide a circuit breaker embodying a single acting shock absorber which is related to the breaker mechanism to retard movement of the breaker in both opening and closing directions.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

Figure 1 is a side elevational view, partly in section embodying the principles of the invention.

Fig. 2 is a front elevational view, partly in section of the operation mechanism.

Fig. 3 is an enlarged detail view showing the shock absorber and its connection to the breaker operating mechanism.

Fig. 4 is an elevational view, partly in section showing the shock absorber.

Fig 5 is an enlarged sectional view showing the dashpot piston and valve.

Referring to Figs. 1 and 2 of the drawings, a storage tank I I mounted within a metal frame I3 is provided for storing gas under pressure. EX- tending from the top of the tank II are three flanged conduits which, in turn, carry metallic valve casings H. A tubular insulator column l9 having a gas passage therethrough is mounted on the upper end of each of the valve casings I! and an arc chute support 2| (only one being shown) also of insulating material is secured to the upper end of the tubular insulator [9. The support 2| has mounted thereon a stationary contact 23 (Fig. 1) provided with an external terminal connector 25. An arc chute 2! is also secured to the support 2| and the forward side of the arc chute is provided with a suitable opening (not shown) through which a movable contact blade 29 is operated into and out of engage- -'ment with the-stationary contact 23. .The lowerportion of the movable contact blade is blIllrcated and the two legs thereof are pivoted at 3| to a conducting bracket 33 securely clamped about the tubular insulator l9. A terminal connector 35 extends from the righthand side (Fig. l) of the bracket 33, and serves, together with the terminal connector 25, to connect the interrupter in an electrical circuit.

The operating mechanism, indicated generally at 31, which is of the compressed gas operated type, is mounted within the frame l3 and includes an operating cylinder 39 (Figs. 1 and 2), an operating piston 4i reciprocably movable therein and a connecting rod 43. The connecting rod 13 is pivotally connected at its upper end by means of a coupling to a pair of spaced arms il secured to an operating shaft 49 journalled in brackets 5i secured to the storage tank ll.

Arms 53 (Figs. 1 and 2), secured at spaced intervals to the shaft 49, are connected by means of insulating operating rods 55 to the movable contact arms 29 for the three poles of the breaker. The lower end of the connecting rod 43 is pivotally connected to a coupling member 51 which is secured to the piston M by means of a nut 59. A cylindrical guide member 6! threadedly engages an enlarged portion of the coupling 51 and extends upwardly through an opening in the upper end of the cylinder 39 forming an air-tight closure for the cylinder.

Each of the arms 53 is provided with a cam surface 63 which cooperates with a roller 65 carried by one arm of a bell crank 61. The bell crank 6'! is pivoted at $9 on a suitable support and the other arm thereof can be brought into engagement with the stern H of a blast valve (not shown) suitably mounted in the housing H. The blast valve normally closes an air blast passage in the insulator l9 and is opened by the cam 63 to admit a blast of compressed gas from the storage tank ll through the insulator [9 to extinguish the are drawn when the contacts separate.

The movable contact blade 29 is moved to the open position by the admission of compressed gas to the cylinder 39 above the piston M which --moves the piston downwardly to the position in which it appears in Fig. 2. During the downward movement of the piston 4|. the shaft 49 is rotated in counterclockwise d rection by means of the connecting rod 43, and this movement of the shaft 49, acting through the operating rods 55, moves the contact'blades 29 to the open position.

Upon admission of compressed 'gas to the cylinder 39 below the pistonM, the piston will be moved upwardly in the cylinder reversing the "above-described operation and actuate the mov- G0:

able contact blade 29 to the closed position. In

the closed position, the arms 53 and the associated operating rods 55 form slightly overcenter toggles which maintain the contact blades 29 in the closed circuit position.

Compressed gas is admitted to the cylinder 39 to open and close the contacts by means of an opening inlet valve 13 (Fig. 2) and a closing inlet valve 15, both inlet valves being electromagnetically operated, and a control valve device indicated generally at 16. The valves 13 and 15 are connected to the storage tank II by means of pipes 11 and 19 (Fig. l). The valve 13 communicates by means of a pipe BI to a passage 33 in a housing 85 secured to an offset portion 8! of the cylinder 39. The passage 83 communicates with the upper end of a valve cylinder 89 and a passage 9I connects the cylinder 89 to the upper end of the operating cylinder 39. The upper end of the operating cylinder 39 also is provided with an exhaust port 93 which is normally closed by H means of a cup-shaped piston type valve 95 forum ing a part of the control valve device 16.

The valve 15 is connected by means of a. pipe 91 to a passage 99 in a housing 50! which is secured to an offset portion I03 of the main operating cylinder 39. The passage 99 communicates with the lower end of a valve cylinder I95 and this cylinder communicates with the lower end of the operating cylinder by means of a passage I01, communication between the passages 99 and I01 being normally closed by means of a cupshaped piston type valve I09. The passage I 01 also communicates with the atmosphere through an exhaust port III. The piston valves 95 and I09 are mounted on opposite ends of a common valve rod M3 for simultaneous operation. The piston valves 95-!09 are made hollow to limit their mass and provide for high-speed operation thereof.

Assuming the breaker to be in the open position as shown in Fig. 2, operation of the closing inlet valve 15 admits compressed gas from the storage tank II through pipes 11 and 19, valve 15 and pipe 91 to the passage 99 below the piston valve I09 moving the control valve device 16, to the uppermost position. The valve 95 in its upper position closes off the inlet passages B3-9I and opens the exhaust port 93. When the valve I99 moves to its upper position, it closes the exhaust port III and opens the communication between the passages 99-401 thereby admitting compressed gas to the operating cylinder 39 below the piston II to close the breaker. After the breaker is closed and the closing air below the piston 45 has bled to atmosphere, the control valve device 19 drops of its own weight to the lowermost position as shown in Fig. 2. In this position of the valves 95-I09, the inlet passage 93-9I is open in readiness to admit a charge of opening gas upon opening of the inlet control valve 13.

The opening operation of the circuit breaker always takes precedence over a closing operation, that is, if the breaker closes in against a fault and the valve 13 is opened to admit a charge or" opening gas to the cylinder 39 above the piston, the operation of the breaker will be quickly reversed and the breaker operated to the open position irrespective of the closing gas in the cylinder below the piston 4|, This trip-free operation is accomplished by makin the piston valve 95 of larger diameter than the piston valve H39. Consequently when, during a closing operation, the valve 13 is opened to admit compressed gas through the passage 9I--83 to the top of the piston valve 95. Due to the larger area of the valve 95, the compressed gas admitted above this valve overcomes the pressure below the smaller valve I99 and quickly forces the control valve device is downward to the lower positions. This quickly closes oil the inlet passage 99 I01. opens the eXhaust port III to dump the closing charge of gas, closes the exhaust port 93 and opens the inlet passage 03-9I to admit compressed gas to the cylin er 39 above the piston 4|, thus quickly revisin t 1e direction of movement of the breaker mechanism and moving the breaker to the open position.

It will be observed that when compressed gas is admitted to the operating cylinder 39 on one side of the piston 4|, the exhaust port 93 or I II on the opposite side of the piston 4| is quickly opened by operation of the control valve device 15. This prevents trapping of gas on the non-working side of the piston which would slow down the operation of the breaker, thus providing for high-speed operation of the breaker to both open and closed positions.

In order to prevent slamming of the breaker parts, it is desirable to decelerate the movement of the breaker mechanism at the end of both opening and closing strokes. Dashpots and shock absorbers have been employed heretofore for decelerating the moving parts of the c rcuit breakers. However, in the past when deceleration was required at the end of both the opening and closin strokes, two dashpots were employed and these were suddenly engaged by the moving parts in a definite position in the stroke.

One of the features of the instant invention is the provision of a single shock absorber of the single-acting type connected to the operating mechanism of a circuit breaker in a manner to effectively decelerate the mechanism during the latter portion of both opening and closing strokes without sudden jerks or slamming of the parts. The single shock absorber, indicated generally at H5, is rigidly mounted on a channel member II1 forming a part of the metal frame I3. The shock absorber I I5 is provided with an operating shaft I I9 to which is rigidly secured an operating arm I2I. The arm IZI is pivotally con nected by means of a pair of links I23 to an arm I25 rigidly secured to the breaker operating shaft 49.

Referring to Fig. 4 of the drawing, a cam I21 disposed within the shock absorber housing is rigidly secured to the shaft II9 for movement therewith. The cam I21 is adapted to bear against a pad I41 mounted on a spider I49 formed integral with the end of a cup-shaped piston I29 disposed for movement in a cylinder I 3| formed integral with the shock absorber housing. A compression spring I33 having one end bearing against the inside of the piston I29 and the other end seated against the bottom end of the cylinder I33 biases the end of the piston against the cam I21 and serves to return the piston following an action of the shock absorber. Disposed within the cup-shaped piston I29 is an intake valve I35 normally biased by means of a spring I31 to the closed position. The spring I31 is compressed between the valve I35 and a spring retainer I39. The end of the piston I 29 is provided with a plurality of fluid passages, indicated at I II which permit fluid to flow through an opening I 5| in the upper end of the piston I29 into the cylinder I3I from a reservoir I42 during the return stroke of the piston.

A relief valve, indicated generally at I, Is

provided to control the flow of fluid out of the cylinder I3I during a compression stroke of the piston I29 to thereby control the retarding action of the shock absorber. The relief valve I43 is arranged to permit a small flow of fluid out of the cylinder during a relatively slow action of the shock absorber without opening the relief valve, but, upon the occurrence of a sudden heavy shock, the relief valve I43 opens, compressing a sprin I45 which normally biases the valve closed, and permits a greater flow of fluid out of the cylinder I3I into the reservoir I42.

Referring to Fig. 3, the parts are shown in full lines in the closed circuit position of the breaker and are shown in dot and dash lines in the open circuit position of the circuit breaker. As viewed in Figs. 3 and 4, the shock absorber I I 5 is efiective to decelerate the movement of the shaft 49 and the breaker mechanism only when the shaft I I9 is rotating in clockwise direction, and is ineffective to restrain movement of the breaker mechanism when the shaft H9 and the cam I2'I are rotated in a counterclockwise direction.

When the circu t breaker is operated to open position. the main shaft 49 together with the arm I25 (Fig. 3) rotates in a counterclockwise direction. During the first part of the opening movement, the arm I25, acting through the link I23, rotates the arm I2I and the shock absorber shaft H9 in a counterclockwise or non-restraining direct on. When the toggle formed by the link I23 and the arm I25 crosses overcenter to the left of a line, indicated at A. drawn through the center of the shaft 49 and the pivoted connection of the link I23 to the arm I2I the direction of movement of the arm I2I is reversed and it starts slowly to move in the opposite or clockwise direction, hence the shock absorber offers little or no opposition to the opening movement of the circuit breaker until the accelerating period is over. The velocity of the arm I2I gradually increases, and the shock absorber becomes increasingly effective during the latter portion of the Opening movement to decelerate the movement of the breaker mechanism, with maximum deceleration near full open position.

When the circuit breaker is operated to the closed circuit position, the arm I25 is moved in a clockwise direction from the position indicated by dot and dash lines at I25 (Fig. 3) to the full line position. During this movement, the arm I2I is rotated in a counterclockwise direction from the position indicated at I2I. In this direction of operation, the shock absorber H5 is ineffective to restrain the closing movement of the breaker mechanism. However, at about the time the contacts touch, the toggle I23--I25 moves overcenter to the right of the line A, reversing the direction of movement of the arm I2I and the shock absorber is operated in the direction in which it is effective to retard the closing movement of the breaker mechanism.

The working pressure is maintained in the operating cylinder over the entire opening and closing strokes and also after the full open and closed positions have been reached. The purpose of maintaining full gas pressure after the contacts reach open position is to prevent rebound of the contacts toward closed position. During a closing operation, when the breaker is attempting to .3

close in against heavy magnetic forces or stalling overloads, the full closing pressure is available. Maintaining the closing air pressure after the breaker is fully closed prevents rebound of the toggle 53-55 from rebounding overcenter and thus holds the breaker closed. If, as previously described, the breaker closes in against a fault of sufficient magnitude, this breaker is immediate ly tripped open by operation of the control valve device 16 which dumps the closing air pressure and admits compressed gas above the piston to operate the breaker to the open position. After an opening or a closing operation is completed, the working pressure leaks out to the atmosphere.

It will be obvious that there is provided a single shock absorber of the single-acting type applied to a circuit breaker in a novel manner to decelerate movement of the breaker mechanism during the latter portions of both opening and closing strokes. The resistance or the shock absorber is applied gradually in both directions, consequently there is no sudden shock or jerk on the mechanism. Due to the toggle connection of the single-acting shock absorber to the breaker mechanism, the maximum decelerating force is applied near the full open and full closed positions which permits the full accelerating force to be maintained until the end of the stroke.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof without departing from some of the essential features of the invention.

I claim as my invention:

1. In a circuit breaker comprising a switch member movable to open and closed circuit positions, operating mechanism including a pivoted crank arm operable in opposite directions to effect opening and closing movements of said switch member, a dashpot operable in one direction to apply a retarding force and being inefiective to apply a retarding force when operated in another direction, an operating arm on said dash-- pot, connecting means connecting saidoperating arm and said crank arm having its line of action on said crank arm movable overcenter relative to the pivot of the crank arm so that movement of said crank arm in either direction first causes said operating arm to actuate said dashpot in ineffective direction and then in a di rection to apply a retarding force to said crank arm.

2. In a circuit breaker comprising a switch member movable to open and closed circuit positions, operating mechanism including a crank arm movable in two directions to effect opening and closing movement of said switch member, a dashpot operable in one direction to apply a retarding force and being ineffective to apply a retarding force when operated in another direction, an operating arm on said dashpot, and a link connect ng said crank arm to said operating arm, said link and said crank arm forming a toggle movable overcenter upon operation of ,said crank arm in either direction to first move said operating arm in ineffective direction and then to move said operating arm in a direction to apply a decelerating force to said operating mechanism.

3. In a circuit breaker comprising a switch "member movableto an open and a closed circuit position, power operated operating mechanism including a crank arm operable in two directions to effect-opening and closing movements of said switch member, a. dashpot operable in one direction to apply a decelerating force to said operating mechanism, said dashpot being i5 inefiective when operated in the other direction to apply a decelerating force, an operating arm on said dashpot, and a link connecting said crank arm to said operating arm, said parts being con structed and arranged so that movement of said crank arm in either direction first moves said operating arm in ineffective direction and then moves said operating arm in a direction to cause said dashpot to apply a decelerating force to said operating mechanism.

4. In a circuit breaker, the combination of a switch member movable to an open position and to a closed position to open and close said circuit, power operated operating mechanism including a crank arm movable in two directions for moving said switch member to said open and closed positions, means comprising a single-acting dashpot for absorbing the kinetic energy of the moving parts of the circuit breaker, an operating arm on said dashpot and a link at all times connecting said crank arm to said operating arm,

positions to open and close the circuit, operating mechanism including a shaft operable in two directions to move said switch member to open and closed positions, power operated means for operating said shaft, a crank arm movable with said shaft, means comprising a single dashpot of the single-acting type for absorbing the kinetic energy of the moving parts of said circuit breaker, and a link operatively connecting said dashpot to said arm and movable overcenter to cause said dashpot to apply a decelerating force to said shaft during the latter part of the movement of said arm in either direction.

6. In a circuit breaker, the combination of switch means movable to open and closed positions, power operated operating mechanism including a crank arm movable in two directions for moving said switch means to open and to closed positions, a dashpot of the single-acting type for absorbing the kinetic energy of the moving parts of said circuit breaker, a rotatable operating arm on said dashpot, a linkage at all times operatively connecting said crank arm to said operating arm, said linkage being movable overcenter to cause said dashpot to apply a decelerating force to said operating mechanism when said operating mechanism moves in either direction, said linkage causing said operating arm to move first in reverse direction and to then apply the decelerating force near the end of each operating stroke.

7. In a circuit breaker, the combination of switch means movable to open and closed positions, power operated means including a crank arm movable in two directions for moving said switch means to open and to closed positions, a single dashpot of the single-acting type for absorbing the kinetic energy of the moving parts of the circuit breaker during both opening and closing operations, a rotatable operating arm on said dashpot, a link at all times connected to said operating arm and connected to said crank arm to form a toggle operable overcenter to first operate said crank arm idly in reverse direction 8 and then cause said dashpot to apply a decelerating force to said circuit breaker during movement of said operating mechanism in either direction.

8. In a circuit breaker, the combination of switch means movable to an open and to a closed position, operating mechanism comprising a cylinder and a piston operable therein, a crank arm operable in two directions by said operating mechanism for moving said switch means to both open and closed positions, inlet valve means for alternately admitting compressed gas to said cylinder on opposite sides of said piston to effect movement of said piston to open and closed positions, an inlet passage and an exhaust passage disposed adjacent each end of said cylinder, valve means operable by compressed gas admitted by said inlet valve means to open the inlet passage and close the exhaust passage on the working side of the piston and to simultaneously close the inlet passage and open the exhaust passage on the non-working side of the piston to effect highspeed operation of said circuit breaker, means comprising a dashpot of the single-acting type for absorbing the kinetic energy of the moving parts of the circuit breaker, and a link together with said crank arm forming a toggle operatively connecting said dashpot to said operating mechanism and operable overcenter to cause said dashpot to apply a decelerating force to said operating mechanism during both opening and closing operations.

9. In a circuit breaker, the combination of relatively movable contacts operable to open and closed positions, power means comprising a fluid motor for operating said switch means, a crank arm operable in two directions by said motor to operate said contacts to both open and closed positions, a dashpot of the single-acting type for absorbing the kinetic energy of the moving parts of the circuit breaker and said fluid motor, valve means for energizing said fluid motor to eilect operation of said switch member to open and closed positions, said valve means maintaining said fluid motor energized during the entire opening and closing operations, and a toggle connecting said single-acting dashpot and said crank arm and operable overcenter to cause said single-acting dashpot to apply a decelerating force to said circuit breaker during the latter part of an opening operation and also at about the time the contacts touch during closing operations.

10. In a circuit breaker, the combination of switch means operable to open and closed positions, power operating means comprising a fluid motor for operating said switch means, a crank arm operable in both directions by said motor to operate said switch means to both open and closed positions, valve m ans for energizing said fluid motor and for maintaining said motor energized during the entire opening and closing operations, decelerating means comprising a singleacting dashpot for absorbing the kinetic energy of the moving part of said circuit breaker, an operating arm on said dashpot, said link and said crank arm forming a toggle operable overcenter to cause said dashpot to declerate the moving parts of the circuit breaker during the latter part of both opening and closing operations.

BENJAMIN P. BAKER.

No references cited. 

